1. Field of the Invention
The present invention relates to a digital image processing technique, and more particularly to a method and apparatus for detecting red-eye regions in a digital image.
2. Description of the Related Art
“Red-eye” is a commonly occurring problem in flash photography, and typically occurs when the bright flash light of the camera is reflected from the blood vessels in the eye, giving the eye an unnatural red hue. Recognizing that the quality of photographs can be significantly improved if red-eyes can be fixed, research has focused on replacing red pixels with a more natural eye color once the image areas to be fixed have been indicated. If numerous images are to be processed in this manner, however, for example in a photofinishing lab, requiring an operator to examine each image and outline the red-eyes is difficult.
In view of the drawbacks of requiring operator examination of images to identify red-eye regions, image processing techniques for detecting red-eyes have been proposed. One such image processing technique, disclosed in U.S. Pat. No. 6,278,491 to Wang et al., analyzes an image to determine the location of each face in an image and, if it is determined that the detected face contains an open eye, performs further analysis to determine whether the detected open eye contains a red pupil. If so, the RGB value of each red-eye pixel is changed to a predetermined color. Despite the proposal of automatic red-eye detection techniques such as that disclosed in U.S. Pat. No. 6,278,491, the inventors of this application have found that techniques for improving detection speed and reducing the occurrence of false positives/negatives would significantly enhance the feasibility and quality of automatic red-eye detection and reduction, particularly in high volume operations such as a photofinishing lab.